<% content_for :header_tags do %>
  <%= stylesheet_link_tag 'statistics', :plugin => 'redmine_statistics' %>
<% end %>
<div id = "statistic">
  <div id = "incenter">
    <%= image_tag(@bar_chart, :alt => "抱歉啊！服务器暂时很忙，请稍后再试一下吧！") %>
  </div>
</div>